Decadent, befitting their occupants.
Each cathedral ship caters to the tastes of its original feudal patron, as well. Every last one differs.
Colloquial nickname for the vessels 'true hemophages' took to the stars in, abandoning Earth with herds of captive humans as a food source.
Each cathedral ship was a massive undertaking and is practically a duchy or kingdom in its own right. Most are quite byzantine and ornate in appearance; according to records, only twenty of them launched from Earth on the Day of Kindred Departure, 24th of August 4313AD. Many dozens have since been encountered, suggesting some deep-space vampire league exists somewhere building more, or that more are being built as the 'kingdoms' within the branch off.
Nothing good lurks in them these days.